Simpson Foundation Anchoring: SSTB Cast-In Bolts vs. Titen HD for Existing Concrete

At some point, every wood-framed wall has to be tied into concrete. That connection usually happens at the sill plate, whether you're building on a new foundation, adding onto an existing structure, or converting a garage or other space.

The challenge is that the right anchoring method depends on the concrete you're working with. If you're pouring a new foundation, anchor bolts are installed while the concrete is still wet. If you're attaching to an existing slab or stem wall, that isn't an option. Instead, you'll need a post-installed anchor designed for cured concrete. While both methods accomplish the same goal, they're installed differently, have different load capacities, and fall under different code requirements.

Simpson offers solutions for both applications. The SSTB series is designed for cast-in-place installations during new concrete pours, while the Titen HD is a heavy-duty screw anchor made for existing concrete and masonry. They also offer several specialty products for specific situations, including standoff bases, mudsill anchor sets, post anchor bolts, and sill-to-stem-wall anchor systems.

The sill plate anchor isn't just a mechanical fastener — it's the base of the lateral load path for the entire structure. Seismic forces and wind loads travel through the wall framing, through the holdowns, through the shear panels, and ultimately into the foundation through the sill plate connection. If those anchors can't transfer the load, the path breaks and the structure moves.

IRC Section R403.1.6 is clear on the minimum requirement for anchor bolts in residential construction: minimum 1/2-inch diameter, minimum 7-inch embedment in concrete, spaced no more than 6 feet on center with one bolt within 12 inches of each end of every sill plate section. That's the floor. In high-wind and seismic zones, the structural engineer's plans will specify a higher standard.

Derek Gilbert, P.E., a structural engineer with Simpson Strong-Tie, wrote in the company's SE Blog in April 2025: "Anchor bolts and post-installed anchors that have obtained evaluation reports — published by ICC-ES and IAPMO-UES — provide building officials with the documentation they need during the plan review and inspection process. Products without evaluation reports create ambiguity that can delay projects and create liability." On a permitted job, that documentation is the difference between a clean inspection and a hold.

Cast-in anchor bolts go into the foundation form before the concrete pour. When the concrete cures around the anchor, it creates a mechanical bond that distributes the load into the full depth of the pour. The SSTB (Sill Plate Tie Bolt) is Simpson's cast-in option — an L-shaped bent anchor with a washer and nut that ties the sill plate to the foundation wall or slab.

The L-bend at the bottom of the anchor is what separates a cast-in bolt from a straight threaded rod. The bend provides mechanical resistance against pullout — the concrete has to fail in a cone-shaped fracture pattern above the anchor before the bolt can pull through. That's a much higher resistance than a straight rod's pure bond with the concrete.

SSTB bolts are available in 1/2-inch and 5/8-inch diameters, and in a range of lengths to accommodate different foundation depths and sill plate thicknesses. The "SB" in some model numbers indicates a shorter bolt for shallow conditions. All SSTB models are listed under ICC-ES ESR-2611 for allowable load values in cracked and uncracked concrete.

The standard SSTB bolt requires placement before the pour. Use a template or a story board to hold the bolts at the correct spacing and height — the top of the bolt needs to project above the sill plate by enough thread to seat a washer and nut fully. The IRC minimum is 15 inches above the bottom of the foundation to the top of the bolt thread, but check your foundation thickness and sill plate spec to confirm the projection needed.

The SSTB covers the standard sill plate anchor bolt condition. But there are four other cast-in products worth knowing about when you're dealing with specific job conditions.

The Titen HD is Simpson's screw anchor for installation into existing, cured concrete and masonry. If you're working on an addition to an existing foundation, a retaining wall, a garage conversion, or any situation where the concrete was already placed before you got to the job, the Titen HD is the post-installed option with a published code listing and independently verified load values.

It's a hardened carbon steel screw with a specially designed thread form that cuts into the concrete as you drive it — similar in concept to a concrete screw like a Tapcon, but heavier duty and with significantly higher load ratings. The Titen HD is listed under ICC-ES ESR-2713 for use in cracked and uncracked concrete and in concrete-filled CMU.

You drill a hole with a carbide-tipped bit, blow out the dust, and drive the screw in with a ratchet or impact driver. No epoxy, no expansion sleeve, no waiting for adhesive to cure. On a job where you need to anchor a new mudsill to an existing foundation quickly and get it inspected the same day, that's a significant workflow advantage over adhesive anchor systems.

The Titen HD comes in 1/4-inch, 3/8-inch, 1/2-inch, 5/8-inch, and 3/4-inch diameters, in both hex head and flat head versions, and in carbon steel or Type 316 stainless steel for corrosive environments. Lengths range from 1-3/4 inches up to 6 inches depending on diameter. The bigger diameters get you into load values comparable to the SSTB cast-in bolts in medium-strength concrete.

The choice between a cast-in anchor and a post-installed screw anchor comes down to one question: is the concrete already placed or not?

If you're setting forms for a new foundation pour, use the SSTB. You place the bolts before the pour, the concrete encases the L-bent anchor, and the result is a high-load connection with well-established pullout values. This is the method the IRC and IBC prescriptively call out for anchor bolts in new residential construction.

If the concrete is already there — addition, garage conversion, retrofit to meet current seismic requirements, or any situation where the slab was poured before this project started — you use the Titen HD. Drill the hole, blow out the dust, drive the screw. No waiting for adhesive to cure, no special conditioning requirements, full rated load as soon as the screw is seated.

There are a few situations where the choice gets more nuanced. In seismic zones where an engineer has specified a holdown anchor through the foundation, the SSTB family doesn't cover that condition — you'd be looking at an embedded threaded rod with a coupled top connection, or a cast-in anchor designed specifically for holdown hardware. In those cases, the post-installed Titen HD in 1/2" or 5/8" can substitute as the anchor for the holdown hardware if the load values in ESR-2713 cover the required design load.

Both systems have ICC-ES evaluation reports with published load tables, and comparing them directly requires using the same concrete strength, embedment depth, and load direction. For most residential sill plate anchor conditions — 3,000 psi concrete, standard embedment — here's how they stack up in approximate terms:

• SSTB16 (1/2" x 16"): ~1,715 lb shear, ~2,440 lb tension in 3,000 psi concrete
• SSTB28 (1/2" x 28", deeper embed): ~2,595 lb shear, ~3,620 lb tension
• Titen HD 1/2" x 3-1/4" hex: varies by concrete strength — approximately 2,000-3,000 lb tension, 1,500-2,500 lb shear in 3,000 psi concrete at minimum edge distance (see ESR-2713 Table 4)
• Titen HD 5/8" x 4": higher load values than 1/2" — see ESR-2713 for exact figures by embedment and concrete strength

For prescriptive residential construction, both systems meet the code minimums at standard spacing. For engineered connections with specific design loads — seismic zones, high-wind requirements, or holdown anchor applications — always pull the actual load tables from ESR-2611 (SSTB) and ESR-2713 (Titen HD) and confirm the values for your specific concrete strength and embedment.

• Step 1: Calculate anchor bolt spacing from the structural plans or IRC Table R403.1.6 — typically 6 feet on center, 12 inches max from plate ends.
• Step 2: Mark anchor locations on the top of the form or snap a chalk line on the foundation form. Use a bolt template or a piece of scrap wood with pre-drilled holes at the correct spacing to hold the bolts plumb during the pour.
• Step 3: Set the SSTB bolt so the L-bend points inward (toward the center of the foundation), the embedment depth is correct, and the bolt projects above the top of the foundation by the amount required for the sill plate thickness plus washer and nut.
• Step 4: Pour and consolidate concrete. Vibrate carefully near the anchor locations — aggressive vibration can shift the bolt position before the concrete sets.
  
• Step 5: After the pour, while the concrete is still green, check bolt plumb and position. Make minor corrections before initial set.
• Step 6: After curing, set the sill plate (with sill gasket or sealer per local code), drill through the plate at bolt locations, seat the square plate washer, and torque the nut to the specification in ESR-2611 — typically 40-50 ft-lb for a 1/2" bolt.

• Step 1: Mark anchor locations per the same spacing requirements — IRC R403.1.6 or engineer's drawings. On retrofit work, you're also working around existing conditions like embedded rebar, so probe with a rebar locator before drilling.
• Step 2: Drill a hole with a carbide-tipped drill bit at the diameter specified for the Titen HD size you're using. Hole diameter is critical — it's not the same as the screw diameter. The bit size for each Titen HD is listed in ESR-2713 Table 1. Drill to the minimum embedment depth plus clearance for drill travel.
• Step 3: Blow out the hole with compressed air — minimum two full purge cycles. Concrete dust left in the hole reduces the thread engagement and the effective load capacity. This step is required per the installation instructions in the ICC-ES report.
• Step 4: Drive the Titen HD with a socket driver or impact driver at low speed. High-speed driving can crack the concrete at the edge of the hole before the screw seats. Slow down as the screw approaches full depth. The screw is fully set when the hex head is snug against the washer or plate surface.
• Step 5: For sill plate anchoring, set the plate first, drill through it and into the concrete in one operation if your bit is long enough, then blow out and drive the screw through the plate into the concrete — no need to set anchor locations beforehand if you're drilling through the plate directly.

• Rotary hammer with SDS chuck — for drilling into concrete for Titen HD; 1/2" and 5/8" carbide SDS bits matched to Titen HD model per ESR-2713
• Rebar locator / scanning tool — before drilling post-installed anchors in existing foundations
• Compressed air nozzle — required for hole cleaning on Titen HD installation
• Impact driver or torque wrench — for driving Titen HD and for torquing SSTB nuts to spec
• Socket set — 3/4" and 15/16" sockets for SSTB nuts; hex sockets for Titen HD hex heads
• Bolt template or layout guide — for holding SSTB bolts at consistent spacing and projection during the pour
• Anchor bolt story pole or template board — for setting SSTB bolt projection height before the pour
  
• Chalk line and tape measure — for laying out anchor bolt spacing along the form